This invention relates to yoking apparatus for use in animal milking, particularly the milking of sheep.
It is known to equip a sheep milking parlour with yoking apparatus comprising a framework defining a number of yoke openings, arranged side by side in a row, in which the ewes are held by their necks while being milked. The openings are normally open to the top so that the ewes may enter from above to reach a food hopper or buckets on the far side of the framework from the milking apparatus. Yoking levers pivotally mounted adjacent each openng can be swung down from an inoperative position to an operative closed position over the ewes' necks and then locked so as to trap the ewes until milking is complete. In the known system each yoking lever is shaped to engage the yoking lever of the neighbouring opening to one side when both levers are in the inoperative position. This has the effect of leaving only one opening at a time open for the ewe to enter. Entry of the ewe into that opening causes the lever associated with that opening to swing down to the operative position, freeing the lever associated with the next opening ready for the next ewe. Such an arrangement of interlocking yoking levers is commonly referred to as a cascade system and assists in bringing ewes in an orderly manner into the milking parlour and into the yoke openings without obstructing each other.
Difficulties with such an arrangement include the need to construct the yoke levers and mount them sufficiently accurately that each engages with its neighbour for satisfactory cascaded interlocking operation. An arrangement which operates correctly when new may not do so after heavy use due to wear in pivot bearings and engaging surfaces. A further disadvantage is that the engaging surfaces of the yoking levers are, in the known apparatus, necessarily situated in the region of the yoke openings where they can harm the ewes due to their sharp edges and where they can become dirty and fouled with wool. The locking mechanism is also in the region of the openings and can fail as a result of wool becoming trapped. Indeed, it is possible for the movement of a ewe with wool trapped in the locking mechanism to release the lock during milking. Yet another disadvantage is the tendency for the rotation of a yoke lever towards its inoperative position when the ewes are released after milking to happen so quickly that the portion which engages the neighbouring lever strikes the ewe in the neighbouring opening if she has not already withdrawn from the opening.